Traditional earphone is mainly wire-controlled with an audio plug at one end and at another end connected with a small loudspeaker, which is used to restore sound signal. Generally, the power of the small loudspeaker is 5-10 mW. When assembled, the small loudspeaker can be installed in the small earplug to form an in-ear earphone, and also can be installed in an earmuff to form an on-ear earphone.
With the emergence of Bluetooth technology, traditional earphone gets rid of the restriction of wire. Effective Bluetooth wireless transmission will be realized after installing Bluetooth transmitting circuit on the audio source device and Bluetooth receiving circuit in the earphone. This kind of Bluetooth earphone can effectively receive audio signal within the scope of more than 10 meters.
However, only small loudspeaker with low power is installed on either traditional wire-controlled earphone or this new Bluetooth earphone. Users can hear normal voice only when the earphone is plugged into users' ears or worn on users' ears. Otherwise, the users can not hear normal voice from the earphone. The users may feel uncomfortable after wearing the earphone for a long time with the earphone plugged into the ears or the ears pressed by the ear buffs.